Could Unlicensed LTE Derail Carrier-WiFi Momentum?

Not really. Unlicensed LTE is coming late to the party when there is already a solid base of WiFi devices, therefore, it will face some challenges, one of them is coexistence - it will be very challenging to coordinate the unlicensed LTE radio (synchronous) and the WiFi radio (asynchronous) operating in the same device or nearby. That is, there will be performance penalty when one radio is transmitting and the other is receiving. True, we have over 500 MHz unlicensed spectrum in the 5 GHz band but it will fill rather quickly especially when 11ac is using very wide channels, up to 160 MHz. There is also radar avoidance (DFS) requirement in the 5 GHz band that might further reduce the available spectrum.

On the positive side, currently small-cells are not universal but rather carrier-specific. Indoor venues and enterprises will refrain from deploying multi carrier infrastructure because of duplication of backhaul, power, real-estate, aesthetics, etc. The unlicensed LTE will be able to emulate WiFi "multi-SSID" in the form of "multi LTE VLAN" each routed (IP) to the corresponding carrier, sort of a network-sharing approach which is welcome as the telecom market is transitioning to a commodity market.

I believe that unlicensed LTE will not derail carrier-WiFi momentum, assuming that carriers would like to keep visibility with their subscribers rather than letting them wander to a random AP.